This still-green quartet was just a small-town northern Alabama bar band a year ago. Now Alabama Shakes is one of the most talked-about new rock acts thanks in part to some good fortune (an early anointing by Drive By Truckers’ Patterson Hood) and a whole lot of show-and-prove on stage.

The buzz centers on the dynamic presence and towering voice of singer-guitarist Brittany Howard. On the band’s full-length debut, she’s as good as advertised, singing with an unhinged gusto, threatening to lose her composure -- if not her mind -- any minute, as she leaps into boy-girl narratives with evangelical zeal. She often sounds like she’s having a conversation with a close friend or God, or just telling herself not to give up. “Didn’t think I’d make it to 22 years old,” the now-23-year-old Howard sings on “Hold On.”

The songwriting and arranging are steeped in values drawn from ‘60s and ‘70s music, when rock bands channeled soul and R&B. Think of the Rolling Stones visiting Muscle Shoals, Ala., in the early ‘70s to work with the studio musicians who backed up Aretha Franklin and the Staple Singers -- that seems to be the sweet spot for the Shakes, all of whom are in their early to mid-twenties. The gospel plea “On Your Way,” the call-and-response vocals in the rousing “I Found You,” the rave-up finish to “Be Mine” – these songs pack a wallop because the band knows how to lay back and leave some space in the arrangements, rather than playing all out, all the time.

The rough-hewn production wouldn’t pass muster on a major-label budget: amplifiers audibly hum, voices crack with emotion, a few bum notes crop up here and there. But this band is terrific all the same, changing speeds, rising and falling to keep up with Howard. “You Ain’t Alone” is all about those dynamics, Howard pushing higher to an ecstatic warble and then falling to a whisper, the band shading her every step.

And yet for all that, fans of the band may quibble. There are even better versions of “You Ain’t Alone” on-line from the band’s justifiably lauded concerts. The Shakes are novices in the recording studio, and they sound almost reserved here compared to their live performances. So “Boys & Girls” isn’t the best way to experience Alabama Shakes. But it’s a heck of an introduction.